Ensuring that your progress has been saved is important if you've just started the game. To make sure your game gets saved, you'll need to link your guest account to an email address, Game Center, or Facebook.
Linking your account to an email address
The game will link your account immediately. Your user ID will change from "ios2" to "site2."
Linking your account to Facebook
The game will link your account immediately. Your user ID will change from "ios2" to "fb2."
Linking your account to Game Center
If you haven't used the selected Game Center account with the game before, the linking process will take place immediately. Your user ID will change from "ios2" to "gpgs2."